A wide variety of sprinklers are commercially available for controlling the distribution of water or other fluids in residential and industrial applications. Some of these sprinklers are mechanically complex, and include a relatively large number of interconnected parts to rotate and control the sprinkler nozzle. In some sprinklers, many of the moveable parts, including “control” parts, are in direct contact with fluid impurities or contaminants that may immediately, gradually, or eventually interfere with the sprinkler operation. In addition, some parts are subject to substantial friction or other wear caused by the water pressure itself and the rotation of the sprinkler during use. Among other things, the present invention overcomes these limitations by providing a relatively simple mechanical design having a motion control assembly separated from the fluid contaminants, and generally balances the pressure and friction forces that might otherwise cause undue wear on the apparatus.